Presenation on 'Understanding the water requirements of the power sector', by Anna Delgado from the World Bankat 2014 UN-Water Annual International Zaragoza Conference. Preparing for World Water Day 2014: Partnerships for improving water and energy access, efficiency and sustainability. 13-16 January 2014

1. UNDERSTANDING THE WATER
REQUIREMENTS OF THE POWER SECTOR
the complexities and challenges of determining water use by
different power generation technologies
Anna Delgado Martin, Technical Specialist, the World Bank
adelgado@worldbank.org

2. Huge ranges!
WHY?
SOURCE: IEA WORLD ENERGY OUTLOOK 2012

3. HYDROPOWER
Only Wind and Solar PV have a
negligible impact on water
resources
3
THERMAL POWER PLANTS

4. SOURCE: IEA WORLD ENERGY OUTLOOK 2012

5. 1. The type of cooling system used
2. The efficiency of the power plant
and not that much the type of power plant
Other: climate conditions and other processes in the plant

6. All the waste heat (“loss”) has to be rejected somehow to
the environment. The vast majority of this heat is
rejected to the environment through cooling systems.
Example of Efficiencies:






Flue gas
Natural Gas Combined Cycle: ~50%
Super Critical Pulverized Coal: ~39%
Subcritical Pulverized Coal: ~36%
Nuclear: ~33%
Solar Thermal (Rankine Cycle) : ~32%
Old coal power plants: as low as 20%!
less cooling
needs
more cooling
needs
Other
Heat to be
dissipated
through cooling
system
The more efficient  the less heat losses 
Less cooling needs
Electricity
Example of heat balance of fossil fuel
power plant
SOURCE: WATER FOOTPRINT OF ELECTRIC POWER GENERATION: MODELING ITS USE AND ANALYZING OPTIONS FOR A WATER-SCARCE FUTURE. DELGADO, 2012.

7. Example of Pulverized
Coal Power Plant
Efficiency: 36.8%
Example of Pulverized
Coal Power Plant with
Carbon Capture and
Storage
Efficiency: 28.4%
SOURCE: WATER FOOTPRINT OF ELECTRIC POWER GENERATION: MODELING ITS USE AND ANALYZING OPTIONS FOR A WATER-SCARCE FUTURE. DELGADO, 2012.

8. Once-through cooling
Dry cooling
SOURCE: RUTBERG, 2012 AND DELGADO, 2012
Cooling Towers

9. Withdrawal
Consumption
US data does not include hydropower or nuclear
In the US there are still a lot of old plants and once through cooling systems
Source: US freshwater withdrawals and consumption (USGS 2005 data)

10.  Retirement of less efficient and older power plants
 Cost of electricity could increase
 water withdrawal/consumption totals would change
Impact of
banning once
through
Source: own estimations

11. Non-cooling process water uses
Flue gas
desulfurization
Bottom ash
handling
Gasification /
Water Gas Shift
Mirrorsurface
washing
Boiler feedwater
makeup
C + H2O 
CO + H2
CO + H2O 
CO2 + H2
Coal
Coal
IGCC (Coal or
biomass)
Solar
All steam-cycle
~200 L/MWh
(consumed)
~100 L/MWh
(reusable)
~200 L/MWh
(consumed)
~20 L/MWh
(consumed)
~20 L/MWh
(reusable)
Compare to ~2000
L/MWh consumed in
typical cooling tower!
But even small water
streams can incur large
economic costs, e.g. Hg
removal for discharge…
SOURCE: WATER FOOTPRINT OF ELECTRIC POWER GENERATION: MODELING ITS USE AND ANALYZING OPTIONS FOR A WATER-SCARCE FUTURE. DELGADO, 2012.

12. Heat Rate vs. Water Use
For a given cooling
system:
Heat Rate
explains most of the
variation between
Cases
Most of the water is
used for cooling
purposes
(85% to 95%)
WATER WITHDRAWAL VS HEAT RATE FOR DIFFERENT POWER PLANTS WITH COOLING TOWERS
SOURCE: WATER FOOTPRINT OF ELECTRIC POWER GENERATION: MODELING ITS USE AND ANALYZING OPTIONS FOR A WATER-SCARCE FUTURE. DELGADO, 2012.

13. Misleading quotes
from articles and
reports
“Wind and solar energy consume
little to no water and generate
negligible carbon emissions”.
“According to the DoE's National Renewable
Energies Laboratory, whose figures are cited in
the report, a typical hydroelectric power plant
uses between 15,000 and 68,000 litres of water
per megawatt hour generated, while a typical
concentrating solar plant – which uses mirrors to
focus sunlight onto a small area – uses about
3000 litres of water per megawatt hour of
electricity generated.”
SOURCE: Stanford, 2013. water energy literature review
“Wet-cooled concentrated solar
power plants use slightly more
water than coal and natural gas;
however, concentrated solar
power plants can be designed to
use dry-cooling, thereby
reducing water demand by more
than 90%. “
SOURCE: Forbes, 2013

14. Misleading quotes from
articles and reports
“concentrated solar power consumes large quantities of water”
“Today’s generation of technology and cleaning frequency
assumptions result in CSP consuming approximately five times
more water than a gas-fired power plant, two times more than
a coal-fired plant and 1.5 times more than a nuclear plant”
“water intensive nuclear power stations should be replaced by renewables
and natural gas, which consume less water”.
“The figures also show that a nuclear power plant uses 2650 litres per megawatt
hour, whereas a typical coal fired power plant uses 1900 and a natural gas plant
750.”

15.  Most of power in the world is generated by thermal
power plants
messages
 Water use in thermal power plants is dominated by
cooling
 The amount of water required for cooling will depend on
the cooling system used
 Given the same type of cooling system, the amount of
cooling water consumed is mainly determined by the
power plants’ thermal efficiency, irrespective of the type of
fuel used
 Given the range of efficiencies within the same type of
power plant (old vs new) it is almost impossible to give a
single water factor for a a power plant technology
 Some low-carbon thermal generation technologies, which
tend to be less efficient, may be at risk from a water
availability standpoint or may have to use more expensive
dry cooling systems
 The Water and Energy Nexus is a regional problem
 Need context specific solutions. One solution does not fit
all

16. THANK YOU
UNDERSTANDING THE WATER REQUIREMENTS
OF THE POWER SECTOR
the complexities and challenges of determining water use by different
power generation technologies
Anna Delgado Martin, Technical Specialist, the World Bank
adelgado@worldbank.org